Study On The β- (2-Chloroaryl) -heterrocyclic Ketene Aminals As Synthon By Multicomponent And Tandem Reactions

β- (2-Chloroaryl)-heterocyclic ketene aminals are good synthons in the form of C-C bond and C-N bond because of its high reactivity. They play a significant role in organic synthesis and much attention has been given to them. New strategy of organic synthesis-multicomponent reaction and tandem reaction-can synthesize libraries of compounds with structural complexity and diversity rapidly, by virtue of their convergence, productivity, ease of execution, and generally high yields of products, have become the most enabling synthetic tools in organic synthesis. This thesis focus on building new framework of [1, 8]naphthyridine from high functionalβ- (2-Chloroaryl)-heterocyclic ketene aminals. This method is flexible, which includs the advantages of high chemo- and regioselectivity and high bond-forming efficiency.In this thesis, Tetrahydroimidazo[3,2,1-ij]bezeno[1,8]naphthyridine derivatives unreported in the literatures have been synthesised withβ- (2-chloroaryl)- heterocyclic ketene aminals by the multicomponent and tandem reactions in the presence of Et3N and K2CO3 as catalyst. The reaction conditions including solvent, catalyst and molar ratio were also investigated. The optimal condition was Et3N as catalyst, molar ratio ofβ- (2-chloroaryl) - heterocyclic ketene aminals, ethyl acetoacetate and aldehyde with1: 1.2: 1.2 and acetonitrile as solvent. The intermediate was not separated, and then proceeded intramolecular cyclization reactions in the presence of K2CO3 in DMF to obtain the target compounds in high yields. These reactions were very mild, convenient and effective. One intermediate (4c) and 15 target compounds (5a-o) were synthesized.Then,β- (2-Chloroaryl)-heterocyclic ketene aminals react with aldehyde and Meldrum's acid to get a new skeleton of 1, 8- naphthyridine. One intermediate (7c) and 12 target compounds (8a-l) were synthesized.In this reaction, seven different active sites were involved; three new bonds and two new rings were constructed with all reactants which efficiently utilized via a sequence of Knoevenagel condensation, aza-ene reaction, cyclization and intramolecular nucleophilic substitution reactions. It fully reflects the"atom economy"in this reactionThe structures of all the target compounds were confirmed by IR, 1 H NMR, 13 C NMR, and HRMS, and the plausible mechanism was also presented. The unambiguous molecular structure of 5c was determined by X-ray diffraction analysis.